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SubjectRe: [ltp] IBM HDAPS Someone interested? (Accelerometer)
On Sat, Jun 25, 2005 at 01:13:17PM -0500, Alejandro Bonilla wrote:

> I have a question here, how do you guys think that the head is parked,
> is it done by the controller directly, which then sends the command to
> the HD to park the head, or this is done by the operating system in some
> kind of way?
> I think the OS or user space is too slow like to react to send a park
> command to the hard drive, so this most be done directly by the embedded
> controller, but still I think it needs some input from the OS, to
> initialize it's settings.

The only way to park a drive is to send a command to it through the IDE
interface. This can't be done by the controller itself, since the
controller in the ThinkPad is a classic Intel ICH chip which only passes
commands around.

The OS is definitely fast enough for this kind of task, it's doable even
in userspace, although not easy.

> i.e. after all, in windows you do have the settings in the software
> for HDAPS, but it looks like it is _not_ managed by the operating
> system at all if there is some type of action to be taken. This is
> also probably why HDAPS won't kick in until booted, and that is
> because it needs to load its config setup by the software.

> This is what I think, please correct me if I'm saying something crazy.

It is definitely all done by the windows kernel driver.

Vojtech Pavlik
SuSE Labs, SuSE CR
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